Planar air pallets have evolved over the years for supporting a load for a relatively frictionless transport over a fixed support surface by means of an air film between the planar air pallet and the underlying support surface. Such structures employ in many cases a single sheet of flexible plastic film bearing the perforations which unrestrictably open to an internal plenum chamber into which the air passes to form the air bearing. They are the subject matter of U.S. Pat. Nos. 3,948,344 and 4,155,421 to Raynor A. Johnson and William D. Fletcher issuing Apr. 6, 1976 and May 22, 1979, respectively.
Such planar air pallets are characterized by a relatively rigid planar backing member normally bearing the load (or formed by the load itself) about the edge of which are sealed the edges of a single sheet of flexible plastic film which underlies the load and the backing member and overlies the support surface with the sheet being perforated centrally and except the perimeter. The sheet forms with the backing member an air bearing plenum chamber. An air tube or hose is coupled to a fitting usually borne by the relatively rigid planar backing member or within the flexible sheet or film bearing the perforations at a non-perforated area to permit air pressuration of the air bearing plenum chamber. Pillowing of the sheet portion of the plenum chamber is controlled to permit jacking of the load sufficiently to accommodate surface irregularities for both the load support surface and the backing surface. In another form, the air pallet comprises a flexible film bag, the bottom of which carries the perforation and the top of which is affixed to the bottom of the load itself.
Air dispersion means are required to ensure dispersion of the air from the air inlet to the extremities of the air bearing plenum chamber to effect the two-fold function of initially jacking the load and permit the air to reach the perforations within the thin flexible bottom sheet to form a thin film air bearing between that sheet and the underlying support surface. Difficulties have been encountered in effecting full and complete air dispersion throughout the plenum chamber, and in effecting jacking without inclining the relatively rigid backing member and tipping over of the load and without damage and destruction to the planar air pallet.
It is therefore a primary object of the present invention to provide an improved load stable dynamic gas pressurized jacking structure of simplified construction and such jacking structure as employed as an element of and in conjunction with planar air pallets.